1. Field of the Invention
The present invention generally relates to selected phase change ink compositions containing the combination of ink colorants with certain phase change ink carrier compositions containing hydroxy-functional fatty amides.
2. Brief Description of the Related Art
In general, phase change inks are in the solid phase at ambient temperature, but exist in the liquid phase at the elevated operating temperature of an ink jet printing device. At the jet operating temperature, droplets of liquid ink are ejected from the printing device and, when the ink droplets contact the surface of the printing media, they quickly solidify to form a predetermined pattern of solidified ink drops.
The phase change inks generally comprise a phase change ink carrier composition which is combined with a phase change ink compatible colorant. Preferably, a colored phase change ink will be formed by combining the above described ink carrier composition with compatible subtractive primary colorants. The subtractive primary colored phase change inks of this invention comprise four component dyes, namely, cyan, magenta, yellow and black. U.S. Pat. Nos. 4,889,560 and 5,372,852 teach the subtractive primary colorants employed typically may comprise dyes from the classes of Color Index (C. I.) Solvent Dyes, C. I. Disperse Dyes, modified C. I. Acid and Direct Dyes, and a limited number of C. I. Basic Dyes. Also suitable as colorants are appropriate polymeric dyes, such as those available from Milliken & Company as Milliken Ink Yellow 869, Milliken Ink Blue 92, Milliken Ink Red 357, Milliken Ink Yellow 1800, Milliken Ink Black 8915-67, uncut Reactint Orange X-38, uncut Reactint Blue X-17, and uncut Reactint Violet X-80.
Phase change inks are desirable for ink jet printers since they remain in a solid phase at room temperature, during shipping, long-term storage, and the like. Also, the problems associated with nozzle clogging due to ink evaporation are largely eliminated, thereby improving the reliability of ink jet printing. Furthermore, since the ink droplets solidify immediately upon contact with the substrate, migration of the ink along the printing medium is prevented and dot quality is improved. This is also true of the processes and ink compositions described herein.
U.S. Pat. No. 5,372,852 teaches that the selective phase change ink compositions described therein contain a phase change carrier composition comprising a fatty amide-containing material (either a tetra-amide compound or mono-amide or mixtures thereof). This patent further teaches the preferred tetra-amide compounds are made by reacting a fatty acid, a diamine (ethylene diamine) and a dimer acid. The preferred fatty acid is taught to be stearic acid and the preferred dimer acid a hydrogenated oleic acid dimer product known as EMPOL 1008 Dimer Acid, manufactured by the Emery Division of Henkel Corporation of Cincinnati, Ohio. The preferred mono-amides are taught to be secondary mono-amides such as behenyl benenamide and stearyl stearamide, products made under the KEMAMIDE trademark by Witco Chemical Company.
While the phase change ink compositions described by U.S. Pat. No. 5,372,852 have met with great commercial success, there is always a need to improve those inks for more demanding processing conditions and different applications.